本研究的目的是要探討冠狀動脈血管支架在歷經氣球導管的擴張以及收縮後在血管支架的長軸及圓周方向的回縮率、長軸縮短率、Dogboning effect及其應力分佈狀況，利用有限元素軟體ANSYS建構冠狀動脈血管支架，並加以變更血管支架的幾何設計，模擬血管支架歷經氣球導管加壓擴張，以及卸壓後在各評估參數上的改變，以期能改善血管支架在各方面的表現。

　　在血管支架幾何外型上改變的有，溝槽角度、支架厚度以及在低應力區除料、高應力區圓形除料、高應力區導圓角等幾種型態上的改變。在對血管支架的各種幾何結構改變探討發現，血管支架的結構幾何對其擴張及以各軸向的回縮表現有相當程度的影響，且不同的幾何特性改變所影響的血管支架表現特性不同，由模型中可以發現，對基本模型的修改，如果是位在會影響血管支架擴張時，對長軸變形提供貢獻的有效區域，就會大幅影響血管支架在縮短量(Foreshortening)上的表現，且由變更血管支架溝槽型態的模型中可以發現，強化溝槽角落會造成血管支架Dogboning Effect更加明顯，而弱化溝槽角落則可以改善Dogboning Effect的程度。

　The purpose of this thesis is to investigate the biomechanical responses of coronary stent after the balloon catheter inflation and deflation. The finite element method is used to analysis the coronary stent performance and the evaluate criterions are radial and longitudinal recoil, foreshortening and dogboning effect.

　Furthermore, the stent geometrical parameters are modified to investigate their biomechanical influences. The evaluated geometry parameters include the change of slot angle, the stent thickness, removing the material at the low and high stress region, and rounding the slot corner region. The ANSYS software is used to perform the analysis and the modification of the stent geometry. The loading is applied on the stent through the inflation and deflation of a balloon catheter which induced the stent expansion and elastic recoil. The results showed that the varying of the stent geometry can affect the stent performance. However, different geometrical parameters will have various degrees of influences on different recoil indices.

[1] C.Dumoulin, B. Cochelin, Mechanical behaviour modeling of balloon-expandable stents. Journal of Biomechanics, 2000; 32,1461-1470.
[2] Francesco Migliavacca et al.,. Mechanical behavior of coronary stents investigated through the finite element method. Journal of Biomechanics, 2002; 35,803-811.
[3] Lorenza Petrini et al., Numerical investigation of the intravascular coronary stent flexibility. Journal of Biomechanics, 2004; 37,495-501.
[4] S.N. David Chua et al., Effects of varying slotted tube (stent) geometry on its expansion behaviour using finite element method. Journal of Materials Processing Technology, 2004; 155-156,1764-1771.
[5] S.N. David Chua et al., Finite element simulation of stent and balloon interaction. Journal of Materials Processing Technology, 2003; 143-144, 591-597.
[6] S.N. David Chua et al., Finite element simulation of stent expansion. Journal of Materials Processing Technology, 2001; 120,335-340.
[7] Fre’de’rique Etave et al., Mechanical properties of coronary stents determined by using finite element analysis. Journal of Biomechanics, 2001; 34,1065-1075.

[8] Dougal R. McClean, Neal L.Eigler, Reviews in cardiovascular medicine, 2002; 3(suppl 5),s16-s22.
[9] F. Auricchio et al., Finite element analysis of a stenotic artery revascularization through a stent insertion. Computer Methods in Biomechanics and Biomedical Engineering, 2000; vol. 00,1-15.
[10] Peter J.B. Hubner, harwood academic publishers, Guide to Coronary Angioplasty and Stenting, 1998; Leicester, UK
[11] Campbell Rogers et al., Balloon-Artery Interactions During Stent Placement. Circ Res, 1999; 84:378-383.
[12] H. Brauer et al., Measurement and Numerical Simulation of the Dilatation Behaviour of Coronary Stents. Mat.-wiss. U. Werkstofftech, 1999; 30,876-885.
[13] 戴文鏗,血管支架塑性成型分析,國立中山大學2004;台灣高雄
[14] Wei-Qiang Wang et al., Analysis of the Transient Expansion Behaviour and Design Optimization of Coronary Stents by Finite Element Method. Journal of Biomechanics. Accepted 8 november 2004.
[15] David E. Kandzari et al., Coronary Artery Stents: Evaluating New Designs for Contemporary Percutaneous Intervention. Catheterization and Cardiovascular Interventions, 2002; 56:562-576